Country music legend Dolly Parton is nursing a secret heartache after the beloved uncle who discovered her musical talent was diagnosed with Alzheimer's disease.The 9 to 5 hitmaker has already suffered the loss of her mother Avie Lee to the condition in 2003, and another uncle, Louis Owens, fell ill with the progressive brain disease a few years later. Now Parton, 66, has learned Bill Owens, the man she credits with helping to launch her career, has become the third member of her family to be diagnosed with Alzheimer's. A family source tells America's National Enquirer tabloid, "Dolly was in tears when she learned Uncle Bill had Alzheimer's."